1. Field of the Invention
The present invention relates to a method for preparing a double-sided film containing the step of forming a film in the interface between air and the mixture of a polymer comprising amine group (—NH) and a compound containing phenol or catechol by exposing the mixture on the air.
2. Description of the Related Art
Catecholamines are found ubiquitously in nature. Wetting-resistant, adhesive foot-pads in mussels, neurotransmitters in the brain, melanin bio-pigments in the skin and eyes, squid beaks, and insect cuticles are related examples. In materials science, catecholamines have recently attracted significant attention due to the unprecedented material-independent surface-functionalization properties found in poly(dopamine) (pDA) and poly(norepinephrine). Another important aspect of catecholamines is their participation in catecholquinone-mediated oxidative crosslinking between bio-macromolecules such as polysaccharides and proteins. This biochemistry is the key factor in forming load-bearing, fully organic biomaterials tolerating wear and abrasion during the lifetime of the organism. This chemistry has been widely used to fabricate mechanically strong organic thin films and fibers and to prepare catecholamine-containing hydrogels. Both the achievement of the mechanical properties of pure organic materials similar to or better than those exhibited in inorganic materials, and the precise control of the mechanical properties of polymeric hydrogels are the aims of using catecholamine chemistry. Up to now, as mentioned above, catecholamine research has focused on either controlling the bulk material properties or functionalizing solid-liquid interfaces. However, another important, yet missing domain, the air-water interface, has long been overlooked in catecholamine material science.
The present inventors developed a film that is formed specifically in the interface between air and water by using a macromolecule containing a high amount of amine group (—NH) and a low molecular compound containing phenol or catechol. The present invention describes the interface specific characteristics of catecholamine chemical reaction for the first time. The prepared film is a double-sided film wherein the upper face and the lower face are different from each other. The film of the invention displays catecholamine specific adhesiveness and strong mechanical strength. When there is a mechanical damage on the film, the film can be auto-repaired and thus a new film membrane can be formed. At this time, an additional process can make the film multi-functional. When the film is produced with an enzyme that can oxidize catechol group by using air in a moderate condition, the film can harbor proteins and cells, so that it can be used as a biomaterial such as a haemostatic and also an industrial waterproof agent, making the film multi-purpose or multi-functional. The versatility film of the present invention, thus, is not expensive and the production method thereof is simple and eco-friendly. Therefore, the film of the invention has a high added-value as a novel separation membrane that can replace the conventional separation membrane.